Could Rolls have make the Foka work?

[Hardrada55]

Before WW2, Poland was spending much time and money in trying to develop a small twin-engine two seat fighter-bomber. The PSL 38 Wilk (Wolf) was supposed to provide Poland with an aircraft that could perform the duties of both fighter and dive-bomber. This aircraft was to be powered by two revolutionary engines, the PZL Foka (Seal) engine. The PZL Foka was an air-cooled inverted V-8 engine of 585 cu. inches that was supposed to provide 420 hp (variously 420hp, 450hp or 490hp) at 3800rpm continuously and 450hp at take off. The Foka only weighed 220kg. In tests, the engine only developed 320hp at 3800 rpm.

Foka never developed the hoped for horse-power and the Poles cancelled the PZL 38 Wilk and it's Foka engine in the spring of 1939. The Poles wasted millions of Zloty on the Wilk that probably should have been dedicated to a less ambitious fighter project.

Polish sources refer to the engine overheating because the cooling surface was too small and to cracked crankshaft housings because of engine balance issues.

At almost the same time as the Poles were pinning their hopes on the Foka powered Wilk, in Britain, Rolls Royce had developed a neat little air-cooled sleeve valve 24 cylinder X configuration engine called the "Exe" or Boreas. It had a displacement of 1,346 cu. in. and weighed 694kg. Exe was originally rated at 920hp @ 3800rpm and from all accounts was a reliable engine with room for development.

½ of an Exe would have been about 673 cu. inches, produced about 460hp and weighed about 350kg. Could Rolls Royce have made the Foka, or an engine similar to the Foka, work? ....well enough to power the PZL 38 Wilk?

 

[tomo pauk]

RR was probably capable to perform any reasonable work related to the piston engines. OTOH, perhaps it might be worth to outfit the Wilk with Gipsy engines?
Then again, the fighter, or fighter-bomber on a single 800-900 HP engine will be much less of a hassle cost, and certainly offering more performance.

 

[Piper106]

The Argus As 410 made 460 HP for 315 kg weight. The Poles might have been able to get a license for the Argus As 410.

A V-8 slice of the later As 411 V-12 engine would have been 400 Hp for about 275 kg. But the As 411 was far from ready in 1939.

 

[ChrisMcD]

I agree the Exe seems to have worked out remarkably well considering it was so far away from Roll's key areas of expertise (an air-cooled, sleeve valve!)

But, at that time there were a number of air-cooled engines about.

Rather than trade with the enemy, the Poles should have done a deal with the Czechs for the Walter Sagitta.

Walter Sagitta - Wikipedia, the free encyclopedia

Or even traded up to the Isotta Fraschini Delta

Isotta Fraschini Delta - Wikipedia, the free encyclopedia

 

[nuuumannn]

Could Rolls Royce have made the Foka, or an engine similar to the Foka, work?

Rather than attempting to rectify any issues with the existing engine, since it was a foreign design its likely RR might have built a basic design that was 'better', taking the best bits of the foreign engine and improving on it. Take the Curtiss D-12 engine for example; this was renamed the Fairey Felix in Britain and fitted in that company's Fox day bomber. RR was aware of the D-12 and its advantages, but opted to do a better engine with the benefits of the Felix. This engine became the Kestrel.

 

[Hardrada55]

I thought that Britain and France guaranteed Poland's independence in 1939 and that France and Poland were allies from 1921 to 1940. I know Poland and Czechoslovakia had border clashes in the 1930s.

Anyone have any information on the "Enlarged Dagger", i.e. horsepower? Should have been about 1224ci, up from 1027ci for the regular Dagger.

Design E110 1939 Dagger VIII
24-cylinder 3.13/16" bore x 3.3/4" stroke 1,000 bhp

Design E112 1939 Enlarged Dagger
24-cylinder 4.1/16" bore x 3.15/16" stroke

 

[nuuumannn]

I thought that Britain and France guaranteed Poland's independence in 1939 and that France and Poland were allies from 1921 to 1940. I know Poland and Czechoslovakia had border clashes in the 1930s.

Can't see what that has to do with the current discussion. Rolls-Royce was a private company, therefore the machinations of international politics was not going to interfere with engine sales and dealings with foreign countries. Remember, the Bf 109, He 112 and Ju 87 prototypes were powered by Kestrels and RR bought a Heinkel He 70 as an engine test bed.

 

[Hardrada55]

Napier Dagger and Rolls Royce "Exe" were two very powerful air-cooled engines for their day. The British seem to know something the Poles don't about making the Foka work. It may be that the engine would work out to be a little different from it's real life configuration, i.e. I don't see it having sleeve valves.

 

[nuuumannn]

Napier Dagger and Rolls Royce "Exe" were two very powerful air-cooled engines for their day.

True, but the Dagger was not without its problems. In the late 1930s RR was concentrating on two engines for mass production in the latest military aircraft, the Merlin and the Vulture, with the Peregrine also. The Exe was an experiment with the hope of subsequent orders. Like I said, I'm sure the Foka could have been modified to make work, as RR also had to rectify the Vulture, which proved troublesome and although it took quite a bit of research to sort out the main problems concerning mounting bolts and casing faces not matching, they were solved whilst the Avro Manchester was in production and service.

 

[Shortround6]

I doubt RR could have made the Foka to work as originally specified. Either a gain in weight or a gain in displacement (or both) might be needed. Cooling the cylinders is the major problem followed by strength of the engine. High RPM allows for small cylinders but the reciprocating parts and crankcase have to strong to handle the loads, you can build very large but light weight engines if you keep the RPM down.
A gain of 50-100kg per engine to get the promised power might be perfectly acceptable given the
PSL 38 Wilk's size and configuration. I don't know.